Plant disease under the homeland security microscope

Pam Dillard | May 10, 2004

AMARILLO, Texas - Since the 9/11 terrorist attacks, questions on plant diseases have added significance, said Charles Rush, plant pathologist with the Texas Agricultural Experiment Station at Amarillo.

"Intentional or unintentional introduction of exotic pests or pathogens could directly increase these losses, "Rush said.

Protecting the country's agriculture is vital to food safety, said Rush, who has joined other land-grant university scientists in a national system of diagnostic laboratories charged with protecting homeland agriculture.

The U.S. Department of Agriculture set up the National Plant Disease Diagnostic Network and designated five regional university coordinators: Cornell University for the northeast, Michigan State University for the north central, Kansas State University for the Great Plains, University of California at Davis for the west, and the University of Florida for the southern region. The National Agricultural Pest Information System operated by Purdue University serves as data collection archive.

The Texas A&M University System Agriculture Program connects with the NPDN via the Great Plains and Southern networks. Texas is the only state with two regions.

High Plains production is vastly different from that to the south. Rush's program fits best with the Great Plains Diagnostic Network and its coordination through KSU. He is also an adjunct professor with Texas Tech University, which marks GPDN's southern boundary.

Other GPDN cooperators include: Colorado State University, Montana State University, North Dakota State University, Oklahoma State University, South Dakota State University, Texas Tech, University of Nebraska, and University of Wyoming. A common software platform allows rapid processing of diagnostic requests and information among these units.

As regional bio-security activities have increased, Rush and his associates, Jeff Stein, plant pathologist, and Kim Maxson, plant disease diagnostician, have briefed government congressional and state legislative officials, including those from USDA Plant Health and Inspection Service Plant Protection and Quarantine Division and Texas Department of Agriculture.

Stein said the introduction of invasive species in this country isn't new, but with increased international commerce, the risks are likely to become more common. Two recent arrivals in the U.S. – citrus canker and plum pox – prompted "zero tolerance" quarantines where the affected fruit trees had to be destroyed.

"If an orchard has either disease, the site is essentially gutted and the grower is left with a huge economic loss," he said.

The Great Plains produces 95 percent of the nation's sunflower acres, 84 percent of the sorghum, 73 percent of the wheat, 55 percent of the dry beans, 42 percent of the cotton, and 35 percent of the sugar beets. The region also grows much of the corn, soybeans, potatoes, alfalfa and canola-rape seed.

Wheat takes a large slice of this regional production pie. Karnal bunt, among other pests, is an unwelcome visitor. Texas was one of only three U.S. states with a confirmed threat within its boundaries. From karnal bunt's arrival in 1996 until last year, the disease caused an estimated $350 million loss nationally.

"We're not only concerned over natural occurrences, but now worry about agroterrorism," said Stein. He pointed to Rush's work on many significant plant diseases including sorghum ergot, wheat streak mosaic virus, and rhizomania, a soil-borne virus affecting sugar beets.

Federal and state agencies monitor national borders for plant pest introductions. Still, on occasion, new ones will slip through. Growers often spot these anomalies, Stein explained. Professionals at land-grant universities handle the identification and verification.

"They will access a web-based diagnostic system, report unusual pest occurrences and existing crop conditions or gain other information not normally submitted through other means," he said. An advisory system will provide information concerning pest alarms or weather conditions that could trigger outbreaks.

According to GPDN director Jim Stack at KSU, the web-based Plant Disease Information System is designed to help land-grant personnel submit plant samples, digital images and other details for row-crop pest diagnosis.

The advantages include rapid evaluation and reporting of potential threats, and shorter response time for diagnoses. Linking satellite labs across the country with regulatory agencies, including the USDA-APHIS and each state's department of agriculture is under way, Stack said.

Recently the Amarillo lab hosted 20 diagnosticians and program coordinators from each state within the network during a site visit and security review in Amarillo. Stein and Maxson trained the diagnosticians in new diagnostic techniques slated for adoption by participating laboratories.

"The fact these professionals from across the Great Plains came here to be trained speaks to the quality of our lab personnel and acknowledges the technical expertise found here," Rush said.

"We're pleased to have Dr. Rush's labs at Bushland and here connected to the Great Plains network," said John Sweeten, Experiment Station research director at the Texas A&M University System Agricultural Research and Extension Center in Amarillo.

The Panhandle-based lab is providing Texas agriculture a regional resource for crop sample processing. Experts there tie plant disease diagnostics to entomology and weed science to provide accurate and rapid assessments of crop pests. Row crop disease surveys through Extension also help monitor the occurrence of many established and exotic plant diseases in the state, Rush said.

The Office of Homeland Security, USDA-APHIS and TDA are underwriting the surveys. For more information about GPDN, and the Texas High Plains Plant Pathology Program, visit these online resources: http://www.gpdn.org and http://thppp.tamu.edu/gpdn/